... Tycho, (see, for example, entries flagged between the Tycho and Hipparcos All 6301 ... Tycho Catalogue 157 Field T48: Flag indicating variability of the Tycho measurements ...
... reduction algorithms should provide improved astrometry (mostly in the reduction of systematic errors) and improved photometry (because the brightest stars on each plate had B and V magnitudes measured by the Tycho experiment on the Hipparcos satellite ...
... The symbols "I" and "R" mean magnitudes in Cousins' I system. "g" designates magnitudes in the system of Thuan and Gunn; "T" stands for broad-band Tycho magnitudes formed from B and V measurements; "r" are red magnitudes not tied to a particular system. ...